This invention relates to devices for lifting an article by means of a vacuum and more particularly for lifting an article of the type that is loosely wrapped in flexible film such as bread and the like.
In lifting and transporting various articles, it is known to utilize a vacuum device commonly referred to as a "Vacuum Cup" or "Vacuum Pad". The devices ordinarily have a vacuum chamber with a lip as a seal for the vacuum. When the article is to be lifted, a vacuum is applied to the vacuum chamber, the lip is brought in contact with the article, and the article is then lifted and transported while being held to the device by the vacuum.
Such prior devices are generally suitable for lifting a rigid planar or contoured surface but not for lifting an article loosely wrapped in flexible film such as a loaf of bread. A problem with using known vacuum devices for lifting articles loosely wrapped in film is that it is either difficult to obtain an effective vacuum seal about the film so that the article may be lifted, or if a seal is obtained, the seal is lost by the film being peeled away from the walls of the vacuum chamber by the weight of the article. When the seal is lost, the article is dropped. Another problem with using known vacuum devices for lifting such articles is that the film may be permanently damaged by being stretched beyond its elastic limit or permanently wrinkled. Wrinkling of the film is undesirable as it may cause the film to become unsightly and resultantly cause any commercial article contained therein to be less saleable.
Therefore, it is the object of this invention to provide a vacuum device which will effectively lift an article loosely wrapped in flexible film.
Another object of this invention is to provide such a vacuum device in which the article being lifted will assist in maintaining a vacuum seal between the film and the walls of the chamber.
A further object of this invention is to provide such a vacuum device that will not damage or permanently wrinkle the film.
Another object of this invention is to provide such a vacuum device which is economical and feasible to manufacture.